In my prior U.S. Pat. No. 4,305,982 I have described a shatterproof laminate adapted to serve as an insulator of light-transmissive character usable, for example, in a skylight or in a greenhouse. The laminate comprises a synthetic-resin panel of skeletal type, with two parallel plates interconnected by spaced-apart webs, bonded onto a glass sheet. Suitable polymeric materials mentioned in the patent include polymethylmethacrylate, polyvinylchloride and polyethylene, which are thermoplastic resins, as well as polycarbonates which could be of either thermoplastic or thermosetting character. A structurally improved skeletal panel is the subject matter of my copending application Ser. No. 541,672 filed Oct. 13, 1983.
Panels or layers of such a skeletal structure are generally produced by extrusion. In some instances several such layers are extruded jointly to form a composite panel.